Switched from cycles to blender, made render turn black and white
Not an answer to your question directly but a possible work-around:
To get a similar look to halo particles still using Cycles Render I often use a material node setup like this. So for a particle system with a kind of basic halo as the particles just create a sphere with this as the material and select object as the particle type under the 'Render' tab and use the sphere you created as the object.
Take note of the 'Blend' value in the 'Layer Weight' node. It was increased from the default 0.5 to about 0.9 to get a softer edge. Tweaking this value, the curve and the emission value should get something to your liking.